Process and apparatus in manufacture of wood pulp



y 9, 1933- 1.. B. DECKER 1,908,324

PROCESS AND APPARATUS IN MANUFACTURE OF WOOD PULP Filed April 4, 1930 By %/M A tto rn ey5 Patented May 9, 1933 PATENT OFFICE LEMUEL B. DECKER, OF KENOGAMI, QUEBEC, CANADA PROCESS AND APIPARATUS IN MANUFACTI IRE OF WOOD PULP Application. filed April 4,

The present invention relates to the manufacture of wood pulp and has particular reference to a process and apparatus for treating wood blocks in the manufacture of mechanical ulp' in association with the digesters employed in the manufacture of sulphite pulp.

An important object of the inventlon 1s the utilization of the overflow or exhaust acid and vapors from chip digesters in a preliminary treatment of the wood blocks or logs to be subsequently ground for the production of mechanical pulp.

A further object of the invention 1's the provision of a process and apparatus for subjecting the wood blocks or logs to a reliminary cooking treatment for the pro uction of a mechanical pulp of a light color suitable for news print paper with or without admixture of sulplhite pulp.

Another object of t e invention is the pro vision of a process and apparatus of the above character which will produce a mechanical pulp of superior qualities.

Still another object of the invention is the provision of a process and apparatus which will result in a substantial economy in the manufacture of pulp for news print paper and thelike.

Other objects and advantages of the m"- vention will become apparent as the tion progresses.

In the accompanying drawing forming a partof this specification and in which like reference characters are. employed to desig-,

nate corresponding parts throughout the same- The figure diagrammatically illustrates'an apparatus suitable for carrying out the inventlon.

With particular reference to the drawing, wherein is shown a preferred embodiment ofthe apparatus, the numerals 10 and 11 designate a pair of digesters commonly employed for the cooking treatment of wood chips, usually called sulphite dlgesters n view of the customary use of a sulphite acid solution for the production of a sulphite ul o the lower ends of the respective didesorip- 1930. Serial No. 441,661.

gesters 10 and 11 are connected pipes 12 and 13 each having a branch pipe 14 and 15 connected with the" intermediate portion thereof and controlled by the respective valves 16 and 17 for the introduction of acid J solution into the digesters. To the lower ends of the pipes 12 and 13 areconnected branch pipes 18 and 19 for the admission of' charge or blow-ofi' from the respective digesters. J

On the top of the digester 10 is removably fitted a-cover 26 having connected to the center thereof an angular pipe section 27 in which is mounted a control valve 28. The

cover and pipe section 27 may be removed as a unit with respect to a coupling section 29 for convenient charging of the digester with chips. A similar cover plate 30 is mounted on the digester 11 having connected thereto a pipe section 31 carrying a control valve 32. The angular sections 27 and 31 make connection with a longitudinal exhaust pipe, generally indicatedat' 33, disposed to conduct the gases exhausted from the digesters and the overflow acid solution to an acid storage tank not shown.

Arranged vertically between the chip difgesters l0 and 11 are a pair of wood block cooking receptacles or digesters 34 and 35 designed to receive therein a chargeof wood logs or blocks out in suitable sizes for grinding. To the lower end of each of the block' digesters 34 and 35 is hingedly connected a-'' closure plate 36 normally secured in a horizontal closing osition by means of a rotatable latch mem er and operable to a downwardly swinging block discharging arrangement. I

I On the top of each of the digesters 34 and 35 is detachably secured a removable cover 37 having connected-therewith a relatively short pipe section 38 which may be removed with the cover to fill the 'digesters with blocks. The pipe sections 38 are normally connectedwith vertically extending pipes 39 connected at spaced positions with the main exhaust conduit 33. A control valve 40 is operatively mounted in association with 5 each of the upwardly extending sections 38.

and carries a valve 44. A stop valve 45 is;

mounted in the exhaust header 33 between the connection of the pipes 39 and 41 therewith. A similar vertically extending pipe 46 extends from the exhaust line 33 to the bottom portion of the digester 35, the lower branch connection having mounted therein a control valve 47, an intermediate branch connection being controlled by a valve 48 and an upper branch carrying a valve 49.

Between the block digesters 34 and 35 is positioned a force pump, conventionally illustrated at 50, preferably of the reversible type, having connection with the digesterv 34 through a pipe line 51 in which is mounted a valve 52 and similarly connected with the digester 35 through a pipe line 53 in which is mounted a valve 54. V

The construction described in the foregoing illustrates a typical battery connection of chip and block digesters, the number of which may be varied in accordance with the working capacity of the mill in which the apparatus is installed.

The process may be carried out by initially filling the chip digester 10 with the wood chips by the removal of the head plate 26 and plpe section 27 connected therewith.

After the digester is filled, the head is re-' placed and bolted tightly in position thereon. The chemical solution, preferably embodying a sulphite acid solution including sulphurous acid, a portion of which is combined with'a metalhc element, is forced into the digester 10' through the branch pipe line 14 by opening the valve 16 and closing the valves in the steam and discharge conduits 18 and 22. Steam is subsequently admitted into the digester by opening the valve 20 in the steam line 18 and closing the valves 16 and 24.

- When the action of the steam has raised the temperature 'and pressure in the digester to a suitable predetermineddegree, this temperature is maintained relatively uniform by opening the escape or relief valve 28 so as to permit the relief or escape of excess gases and overflow acid solution. During the .in-

troduction of the steam into thechip digester 10, the adjacent block digester 34 is filled with blocks by removing the head plate 37, the blocks being in the form commonly cut for the grinding machines. During the cooking operation in the chip digester 10, the valve 45 in the discharge line 33 is closed, the valve 42 in the lower branch line of the connecting pipe 41 is fully opened while the auxiliary elevated branch control valves 43 and 44 are partly opened so that the escape acid and gases from the chip digester are gznducted into the adjacent block digester When the temperature of the acid in the block digester 34 attains a suitable degree,-

somewhat lower than the temperature in the chip dlgester, the escape valve 40 is opened to allow the excess gases and acid to escapeer than the ground wood now procured and I will have a desirable, relatively light color comparable to-the sulphite' pulp requiring a greatly reduced proportion of .sulphite pulp in the manufacture of news print and similar paper. 7

During the simultaneous operation of the chip digester 10 and the block digester 34, the: complementary chip digester '11 and block digester 35 are filled with chips and.

blocks respectively, in the manner indicated inc-the foregoing. When the initial operation is completed, the-exhaust valves 28 and 40 and the control valves 42, 43 and 44 are closed. The blow valve 24 is opened and the contents of the chip digester 10 are blown into a suitable blow pit. Thepump 50 is now actuated so as to pump the acid solution from the block digester 34 into the adjacent block digester 35 so as tosubject the blocks in the latter to a preliminary.

heating treatment. The bottom plate 36 of the digester 34 is then swung to an open position so that the tieated blocks are dropped vinto a suitable receiver.

The cooking operation is then repeated upon the opposed side of the battery, the

acid solution being injected into the digester 11 and the steam subsequently admitted as previously described .-for the digester 10. During the operation of the digester 11, the exhagsted gases and acid are conducted into the adjacent block digester 35 through-the pipe line 46 and by opening the valves 47, 48 and 49.

-to a preliminary cooking treatment, the

quality of the latter is increased-to such an extent that the amount of sulphite pulp required in paper manufacture is greatly reduced and the ultimate cost of the pulp suitable for news print paper is substantially decreased. p

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same in that various modifications in the apparatus and steps of the process may resorted to without departing from the spirit of the invention. or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. The process of manufacturing wood I pulp which consists in conducting the escaped chemical solution from a chip digester to a wood block digester so as to sub ect the wood blocks to a preliminary cooking treatment during the operation of the chip digester prior to grinding the wood blocks.

2. The process of manufacturing wood pulp which consists in piping a plurality of wood chip digesters and wood block digesters in battery, conducting the escaped chemical solution from a chip digester to a wood block digester to cook t e wood blocks during the operation of the chip digester, transferring the heated acid from the wood block digester to an adjacent wood block digester to subject the wood blocks in the latter to a preliminary heating treatment, and cooking the wood blocks in the second wood block digester by conducting the chemical solution from the adjacent chip digester therein.

3. The process of manufacturing wood pulp which consists in utilizing the chemical solution exhausted from a sulphite chip digester during its cooking operation, to subject wood blocks in an ad acentwood block digester to a preliminary cooking operation prior to grinding the said wood blocks in the manufacture of mechanical pulp.

4. The process of manufacturing wood pulp scribed, the combination of aplurality of wood chip digesting vessels, a corresponding number of wood block digesting vessels, pipe lines connecting each of the chip digesting vessels with the block digesting vessels in complementary units, the said pipe lines being disposed so that'the matter discharged from the chip digesting vessels during the cooking operation can be conducted into the block digesters, and means whereby the cooking liquid can be transferred from one block digester to another.

6. In the manufacture of wood pulp, the process which consists in conducting the relief matter discharged from a wood chip treating vessel to a wood block treating vessel to subject the blocks to a preliminary impregnation treatment in the latter.

7. In apparatus for treating wood in the manufacture of pulp, the combination of a be plurality of batteries each consisting of a wood chip treating vessel and a wood block treating vessel, relief pipes connecting each of the vessels with an exhaust header, conduits arranged so that the relief matter of a chip treating vessel may be conducted to the block treating vessel connected in battery therewith, valvular -means for controlling the discharge of relief matter into the block treatingvessels, and a conduit directly connecting block treating vessels of the batteries.

In witness whereof I have hereunto set my.

hand.

LEMUEL B. DECKER. 

